This works to a point but I need to explicitly say stuff like "[online]" and I cannot use note or howpublished more than once. The result is I cannot write complete references for my websites. This is the format I expected to use:

Author/Editor (use the corporate author if no individual author or editor is named)

the use of curly braces in the author field to denote the fact that it's a "corporate" author rather than a person with first name "European", middle name "Space", and surname "Agency",

the use of the \emph{} command inside the title field, which is required because the unsrt bibliography style does not by default italicize the contents of the title field of entries of type @misc, and

the use of curly braces in the title field to prevent BibTeX from rendering the words ESA and ENVISAT in (mostly) lowercase letters.

I ended up working around it slightly differently but either would have done. I did it like this: @misc{esa, author = "{European Space Agency}", title = "\emph{{ESA: Missions, Earth Observation: ENVISAT}{[Online]}}", howpublished = " Available from: \url{envisat.esa.int}", note = "[Accessed: 3rd July 2008]" }
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MagpieOct 28 '12 at 1:11